CN102843764B - Method for outputting synchronization signals accurately to solve problem on synchronization of multi-stations - Google Patents

Abstract

The invention discloses a method for outputting synchronization signals accurately to solve the problem on the synchronization of multi-stations, comprising the following steps: setting the clock of a slave station 1 as a system reference clock, calculating the delay error and the offset error of each slave station when a main station reads the corresponding time value, writing the calculation result into each slave station, sending commands by the main station when the main station starts to synchronize all the slave station, reading the current system time from the reference clock slave station 1, writing the current system time into other slave stations, recording the current time after a slave station n receives the commands, acquiring the local reference clock for outputting pulse and further acquiring the local clock offset delta t, and compensating by the system according to the local clock offset delta t so as to output accurate synchronization pulse. The method overcomes the defects of the prior art and can realize synchronous outputting.

Description

The method of synchronizing signal is accurately exported for solving multistation stationary problem

Technical field

The present invention relates to a kind of method accurately exporting synchronizing signal for solving multistation stationary problem.

Background technology

In prior art, multiple slave stations based on distributed AC servo system cannot be accomplished synchronously, such as, multi-axial Simultaneous in digital control system, and synchronous acquisition inputs, synchronism output and other motion controls synchronous, these all limit the development of distributed AC servo system in synchronous applications.Therefore often distributed AC servo system is not adopted, but be all integrated on master control circuit plate, such way can accomplish Synchronization Control really, but problem adjoint to be thus system too integrated, a lot of problem can be caused, such as cabling is various, poor expandability, be difficult to especially in large scale system realize.

Summary of the invention

In order to overcome the deficiency that prior art exists, the object of the present invention is to provide a kind of method accurately exporting synchronizing signal for solving multistation stationary problem that can realize synchronism output.

For reaching above object, the invention provides a kind of method accurately exporting synchronizing signal for solving multistation stationary problem, comprising the steps:

(1) by the clock T of slave station 1 _refbe set to system reference clock, then

When Frame arrives slave station 1 from main website, slave station local clock T _refmoment be t ₁, the slave station local clock T when Frame arrives slave station n _{local (N)}moment be t _n, and meet: t _n-t ₁=T _{offset (n)}+ T _{delay (n)};

When Frame returns arrival slave station n through follow-up all slave stations, slave station local clock T _{local (N)}moment be t' _n, when Frame arrives slave station 1, slave station local clock T _refmoment be t' ₁, and meet: t'1-t'n=-T _{offset (n)}+ T _{delay (n)};

Wherein: T _{offset (n)}represent the offset error that slave station 1 causes to slave station n because of power-on time, crystal oscillator Induction Peried, T _{delay (n)}represent slave station 1 to slave station n because transmission forwards the delay error caused;

(2) when main website reads corresponding moment value, calculate delay error and the offset error of each slave station, and result of calculation is write in each slave station; Wherein, the delay error of slave station n and offset error are calculated by following formula:

T _delay(n)= （（t' ₁-t ₁）-（t' _n-t _n））/2

T _offset(n)= （（t' _n+ t _n）-（t ₁+ t' ₁））/2；

(3) when main website starts synchronous all slave stations, main website sends instruction, reads present system time T from reference clock slave station 1 _{sys_ref}and write in all the other slave stations, after slave station n receives this instruction, record current time t _local(n), obtain the local reference clock T for exporting pulse _{local_ ref}=t _local(n)-T _{offset (n)}-T _{delay (n)}, and then obtain local clock offsets Δ t=t _local(n)-T _{offset (n)}-T _{delay (n)}-T _{sys_ref}, system compensates T according to Δ t _{local_ ref}thus export accurate lock-out pulse.

As a further improvement on the present invention, main website calculates T at repetitive measurement _{delay (n)}, T _{offjset (n)}mean value after write each slave station to reduce error.

The invention has the beneficial effects as follows: the multiple slave stations based on distributed AC servo system can realize synchronism output, overcome the offset error because power-on time, crystal oscillator Induction Peried cause, factor data transmission forwards the delay time error that causes and to drift about the error caused because of crystal oscillator, thus can be used for the synchronous exigent occasions such as multi-axial Simultaneous.

Accompanying drawing explanation

Accompanying drawing 1 is the method Signal transmissions schematic diagram accurately exporting synchronizing signal according to the present invention for solving multistation stationary problem.

Embodiment

Below preferred embodiment of the present invention is described in detail, can be easier to make advantages and features of the invention be readily appreciated by one skilled in the art, thus more explicit defining is made to protection scope of the present invention.

See accompanying drawing 1, a kind of method accurately exporting synchronizing signal for solving multistation stationary problem, the method comprises the steps:

(1) by slave station 1 clock T _refbe set to system reference clock; Slave station 1 local clock T during Frame arrival slave station 1 _refmoment be t ₁, when data return through follow-up all slave stations, slave station local clock T during arrival slave station 1 _refmoment be t' ₁; Slave station local clock T during Frame arrival slave station n _{local (N)}moment be t _n, when data return through follow-up all slave stations, slave station local clock T during arrival slave station n _{local (N)}moment be t' _n; Suppose that the smooth length of cable TX with RX is consistent, all devices process is consistent with Forwarding Latency, without saltus step, can set up following relation:

T _n-t ₁=T _{offset (n)}+ T _{delay (n)}(1-1 formula)

T'1-t'n=-T _{offset (n)}+ T _{delay (n)}(1-2 formula)

Wherein, T _{offset (n)}represent the offset error that slave station 1 causes to slave station n because of power-on time, crystal oscillator Induction Peried; T _{delay (n)}represent slave station 1 to slave station n because transmission forwards the delay error caused; Note: clock skew is from three parameters of crystal oscillator frequency precision: fixed frequency, temperature drift, ageing rate.Fixed frequency: refer within the scope of actual output frequency, actual meeting deviation is how many, unit ppm; Temperature drift: refer in operating temperature range, frequency meeting deviation is how many, unit ppm; Ageing rate: refer in work after 1 year, frequency meeting deviation is how many, unit ppm.Such as: fixed frequency 25MHZ, positive and negative 10ppm.Refer to that frequency changes within the scope of the positive and negative 250HZ of 25MHZ.

(2) when main website reads the corresponding moment, then calculate delay error and the offset error of each slave station, and these information are write in each slave station;

Can obtain slave station n's

Delay error T _{delay (n)}=((t' ₁-t ₁)-(t' _n-t _n))/2 (1-3 formulas)

Offset error T _{offset (n)}=((t' _n+ t _n)-(t ₁+ t' ₁))/2 (1-4 formulas)

(3) when main website starts synchronous all slave stations, main website sends instruction, reads present system time T from reference clock slave station _{sys_ref,}and write in other slave stations; After slave station n receives this instruction, record present system time t _local(n), now can calculate the local reference clock for exporting pulse:

T _{local_ ref}=t _local(n)-T _{offset (n)}-T _{delay (n)}(1-5 formula)

Now also can calculate local clock offsets:

Δ t=t _local(n)-T _{offset (n)}-T _{delay (n)}-T _{sys_ref}(1-6 formula)

T is compensated according to Δ t _{local_ ref}, eliminate clock skew, export more accurate lock-out pulse.

It should be noted that, in order to reduce error, main website can repetitive measurement, calculates T _{delay (n)}, T _{offjset (n)}mean value after write each slave station, system according to compensate after T _{sys_local}just can export the signal of precise synchronization.Multiple slave stations based on distributed AC servo system can realize synchronism output, overcome the offset error because power-on time, crystal oscillator Induction Peried cause, factor data transmission forwards the delay time error that causes and to drift about the error caused because of crystal oscillator, thus can be used for the synchronous exigent occasions such as multi-axial Simultaneous.

Above execution mode is only for illustrating technical conceive of the present invention and feature; its object is to allow person skilled in the art understand content of the present invention and to be implemented; can not limit the scope of the invention with this, all equivalences done according to Spirit Essence of the present invention change or modification is all encompassed in protection scope of the present invention.

Claims (2)

1. accurately exporting a method for synchronizing signal for solving multistation stationary problem, it is characterized in that, comprise the steps:

(1) by the clock T of slave station 1 _refbe set to system reference clock, then

When Frame arrives slave station 1 from main website, slave station local clock T _refmoment be t ₁, the slave station local clock T when Frame arrives slave station n _{local (N)}moment be t _n, and meet: t _n-t ₁=T _{offset (n)}+ T _{delay (n)};

When Frame returns arrival slave station n through follow-up all slave stations, slave station local clock T _{local (N)}moment be t' _n, when Frame arrives slave station 1, slave station local clock T _refmoment be t' ₁, and meet: t'1-t'n=-T _{offset (n)}+ T _{delay (n)};

Wherein: T _{offset (n)}represent the offset error that slave station 1 causes to slave station n because of power-on time, crystal oscillator Induction Peried, T _{delay (n)}represent slave station 1 to slave station n because transmission forwards the delay error caused;

(2) when main website reads corresponding moment value, calculate delay error and the offset error of each slave station, and result of calculation is write in each slave station; Wherein, the delay error of slave station n and offset error are calculated by following formula:

T _delay(n)= （（t' ₁-t ₁）-（t' _n-t _n））/2

T _offset(n)= （（t' _n+ t _n）-（t ₁+ t' ₁））/2；

(3) when main website starts synchronous all slave stations, main website sends instruction, reads present system time T from reference clock slave station 1 _{sys_ref}and write in all the other slave stations, after slave station n receives this instruction, record current time t _local(n), obtain the local reference clock T for exporting pulse _{local_ ref}=t _local(n)-T _{offset (n)}-T _{delay (n)}, and then obtain local clock offsets Δ t=t _local(n)-T _{offset (n)}-T _{delay (n)}-T _{sys_ref}, system compensates T according to Δ t _{local_ ref}thus export accurate lock-out pulse.

2. the method accurately exporting synchronizing signal for solving multistation stationary problem according to claim 1, is characterized in that: main website is at repetitive measurement and calculate T _{delay (n)}, T _{offset (n)}mean value after write each slave station to reduce error.